Apparatus for cooling hydrogen recirculation blower for fuel cell vehicle

ABSTRACT

The present invention provides an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle the apparatus including: a blower housing including an inlet and an outlet for hydrogen recirculation provided in a front part thereof, and an impeller and a motor for driving the hydrogen recirculation blower provided therein; a cooling passage, through which hydrogen is supplied to the blower housing to provide heat exchange, provided to the blower housing; and a hydrogen supply line, through which hydrogen is supplied to the cooling passage to cool the motor, branched from a hydrogen supply pipe and connected to the blower housing, thereby improving cooling efficiency of the motor and ensuring stability of the fuel cell system.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) on Korean Patent Application No. 10-2007-0070335, filed on Jul. 13, 2007, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Technical Field

The present invention relates to an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle. More particularly, the present invention relates to an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle which improves cooling efficiency of a motor and ensures stability of the system by supplying a portion of hydrogen used as fuel in a fuel cell to a blower housing.

(b) Background Art

In general, a fuel cell used as a main power source of a fuel cell vehicle generates electricity by combining oxygen from the air and hydrogen stored in a fuel tank.

FIG. 1 is a schematic diagram of a fuel cell system for a fuel cell vehicle. The fuel cell 10 includes a separator 11, an anode 12, an electrolyte membrane 13, a cathode 14, a hydrogen/oxygen/coolant distribution structure 15, an anode flow field 16, a cathode flow field 17, and a coolant flow field 18.

During operation of the fuel cell 10, hydrogen is supplied from a hydrogen supply source 19 to the anode flow field 16 of the fuel cell 10 through a hydrogen supply solenoid valve 20 and a pipe 38.

Unreacted hydrogen in the fuel cell 10 is recirculated to a pipe 23 by the operation of a hydrogen recirculation blower 22 in a state where a purge valve 21 is closed and then returned to the anode flow field 16 of the fuel cell 10 through the hydrogen recirculation blower 22 and a hydrogen recirculation control valve 24, thus increasing the availability of hydrogen.

The hydrogen purge valve 21 is opened for a predetermined time period to discharge nitrogen and moisture flowing through the electrolyte membrane 13.

Oxygen is supplied from the air 46 (e.g., ambient air) to an air blower 26 through a pipe 25, and the air blower 26 controls the flow of air in accordance with conditions to supply the air to the cathode flow field 17 of the fuel cell 10 trough a pipe 27.

Hydrogen (H₂) at the anode flow field 16 is separated into hydrogen ions (H⁺) and electrons (e⁻) by a catalyst of the anode 12, and the hydrogen ions are transferred to the cathode 14 through the electrolyte membrane 13. Oxygen (O₂) at the cathode flow field 17 is split into oxygen ions (O⁻) by a catalyst of the cathode 14, and the hydrogen ions (H⁺) and the oxygen ions (O⁻) are reacted with each other to form H₂O.

O₂ contained in the air supplied to the cathode flow field 17 is consumed and thereby the cathode flow field 17 has an oxygen concentration lower than that of the ambient air (there is much more nitrogen present). The resulting air in the cathode flow field 17 is discharged through an air discharge pipe 28.

The fuel cell 10 is cooled by supplying a coolant to the coolant flow field 18. In order to maintain the optimum temperature, a coolant pump 29 is operated appropriately. During operation of the coolant pump 29, the coolant at a high temperature in the coolant flow field 18 is fed into the coolant pump 29 through a pipe 30 for discharging the coolant and then introduced into a heat exchanger 32 through a heat exchanger supply pipe 31, in which the high-temperature coolant becomes cooled.

The thus-cooled coolant is fed back into the coolant flow field 18 by way of a heat exchanger discharge pipe 33, a coolant control valve 34, and a coolant recirculation pipe 35 to cool the fuel cell 10.

Meanwhile, the recirculation in a hydrogen supply system is a significantly important element for improving the efficiency of the fuel cell system, increasing the humidification of a fuel electrode, and increasing the stability and lifespan of the system.

Moreover, in using the hydrogen recirculation blower for the recirculation of the high-temperature mixed gas (such as hydrogen, nitrogen, steam, etc.) discharged from the fuel cell, the capacity of the motor for driving the blower and the other conditions may have a critical effect on the durability of the hydrogen recirculation blower.

However, conventional air cooling methods in which cooling fins are used are restrictive with respect to a motor having a small capacity due to the amount of heat radiation. Also, water cooling methods require additional coolant lines and water pumps, which is unfit to optimization of the system.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.

SUMMARY OF THE INVENTION

The present invention has been made in an effort to solve the above problems, and an object of the present invention is to provide an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle, in which a cooling passage is arranged in a blower housing of the hydrogen recirculation blower such that hydrogen, instead of a coolant, is used to cool a motor.

In one aspect, the present invention provides an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle, wherein a portion of hydrogen, used as fuel in a fuel cell stack, is used as a coolant for cooling a motor of the hydrogen recirculation blower.

In a preferred embodiment, the apparatus comprises a blower housing, a cooling passage and a hydrogen supply line. The blower housing includes an inlet and an outlet provided in a front part thereof for hydrogen recirculation. It also includes an impeller, and a motor provided therein for driving the hydrogen recirculation blower. The cooling passage is provided to the blower housing. Through the cooling passage, hydrogen is supplied to the blower housing for heat exchange. The hydrogen supply line is branched from a hydrogen supply pipe and connected to the blower housing. Through the hydrogen supply line, hydrogen is supplied to the cooling passage for cooling the motor.

Preferably, the cooling passage is disposed on the outer surface of the blower housing in order to cool the motor heated by rotation of the impeller. Also preferably, cooling fins are provided inside the cooling passage such that the hydrogen supplied to the cooling passage cools the cooling fins heated by the heat generated from the motor.

Suitably, a heat insulating plate is provided on the inner wall of the blower housing so as to divide the blower housing into an impeller portion and a motor portion.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like.

Other aspects of the invention are discussed infra.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a conventional fuel cell system for a fuel cell vehicle;

FIG. 2 is a schematic diagram illustrating an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle; and

FIG. 3 is a schematic diagram illustrating the structure of a hydrogen recirculation blower of FIG. 2.

Reference numerals set forth in the Drawings includes reference to the following elements as further discussed below:

10: fuel cell 11: separator 12: anode 13: electrolyte membrane 14: cathode 15: hydrogen/oxygen/coolant distribution structure 16: anode flow field 17: cathode flow field 18: coolant flow field 19: hydrogen supply source 20: hydrogen supply valve 21: purge valve 50: hydrogen recirculation 23, 25, 27, 30, 31, 33, 35 and 38: pipes. blower 24: hydrogen recirculation control valve 26: air blower 28: air discharge pipe 29: coolant pump 32: heat exchanger 34: coolant control valve 36: air discharge solenoid valve 46: air 51: blower housing 52: impeller 53: stator 54: magnet 55: bearing 56: cooling fin 57: cooling passage 58: hydrogen supply line 59: rotational shaft 60: heat insulating plate 61: hydrogen recirculation line

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiment of the present invention, examples of which are illustrated in the drawings attached hereinafter, wherein like reference numerals refer to like elements throughout. The embodiments are described below so as to explain the present invention by referring to the figures.

FIG. 2 is a schematic diagram illustrating an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle, and FIG. 3 is a schematic diagram illustrating the structure of a hydrogen recirculation blower of FIG. 2.

According to a preferred embodiment of the present invention, an apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle is provided, in which a hydrogen supply line 58 is coupled to a blower housing 51 of a hydrogen recirculation blower 50 (hereinafter referred to as the ‘hydrogen blower’), and hydrogen, used as fuel in a fuel cell, is used as a coolant for cooling a motor.

The hydrogen blower 50 is referred to as a hydrogen pump or a hydrogen compressor in accordance with the specification and type thereof and includes an impeller 52, a motor, a blower housing 51, a bearing 55 and a motor controller.

The impeller 52 connected to the motor through a shaft receives a rotational force from the motor to increase the fluid pressure of the coolant flowing through a hydrogen inlet, thus forming the flow of the coolant.

The motor used in the hydrogen blower 50 is a brushless DC (BLDC) motor and operates at a high RPM to satisfy the optimum package. The main elements of the motor include a magnet 54 and a stator 53. The magnet 54 is connected to the impeller 52 through a rotational shaft 59, both ends of which are supported by the bearings 55.

The motor controller communicates with a superior controller to receive a command associated with an operation speed of the overall system and monitors the operation state such as operation speed, power consumption, electric current and torque.

Since an insulated gate bipolar transistor (IGBT) used as a switching element in the motor controller generates a lot of heat, it requires an efficient heat radiation.

According to a preferred embodiment of the present invention, the hydrogen supply line 58 branched from a hydrogen supply pipe 38 is coupled to the blower housing 51 so as to supply the hydrogen as a coolant through the hydrogen supply pipe 38 to the blower housing 51.

A heat insulating plate 60 which divides the inside of the blower housing 51 into an impeller portion and a motor portion is provided in the blower housing 51. That is, two chambers are defined by the heat insulating plate 60, in which the impeller 52 is disposed in the left chamber and the magnet 54 and the stator 53 are arranged in the right chamber.

Cooling fins 56 are formed protruding from the outer surface of the blower housing 51, more precisely, on the outer surface of the right chamber in which the magnet 54 and the stator 53 are disposed, in order to increase the heat radiation area. Accordingly, the hydrogen is supplied to the cooling fins 56 as a coolant to cool the blower housing 51 in which the motor is provided.

A cooling passage 57 shielding the cooling fins 56 from the outside air is formed on the outer surface of the blower housing 51 to supply the hydrogen as a coolant to the cooling fins 56, and an inlet of the cooling passage 57 is connected to the hydrogen supply line 58.

The inlet of the cooling passage 57 is formed on the top of the blower housing 51 so as to be adjacent to the heat insulating plate 60, and an outlet of the cooling passage 57 is formed on the bottom of the blower housing 51 so as to be adjacent to the heat insulating plate 60. The outlet of the cooling passage 57 may preferably be formed separately from a hydrogen outlet of the hydrogen blower 50, or may also preferably be joined directly to the impeller 52 and connected to a hydrogen recirculation line 61.

The hydrogen recirculation line 61, which connects the hydrogen blower 59 and a hydrogen recirculation control valve, may be embodied in a form of a pipe structure, through which the hydrogen used for cooling the motor is configured to be recirculated together with the hydrogen discharged from an outlet of a fuel cell stack.

The operation of the apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle having the above-described structure in accordance with the preferred embodiment of the present invention will be described in detail.

Hydrogen supplied from a hydrogen supply source 19 through the hydrogen supply pipe 38 is supplied to an anode (fuel electrode) 12 of the fuel cell stack as a fuel through the hydrogen recirculation control valve. A portion of the hydrogen supplied from the hydrogen supply source 19 is supplied to the cooling passage 57 of the blower housing 51 as a coolant through the hydrogen supply line 58 branched from the hydrogen supply pipe 38.

In the case where the hydrogen is used as a coolant, the hydrogen is fed into the inlet of the cooling passage 57 of the blower housing 51 through the hydrogen supply line 58, and thus the heat generated from the motor is absorbed by heat exchange with the hydrogen through the cooling fins 56.

Subsequently, the hydrogen heat-exchanged in the cooling passage 57 is discharged through the outlet of the cooling passage 57 and then supplied to the fuel cell stack through the hydrogen recirculation line 61.

The more the recirculation amount of the hydrogen used as a coolant is, the more advantageous the system may be. The present apparatuses make it possible to increase the capacity of the motor and ensure desired recirculation flow.

In general, the temperature of the hydrogen supplied from the hydrogen supply source is about 20° C., and the temperature of the heat generated from the motor of the blower housing is about 75° C. The temperature of the hydrogen heat-exchanged in the cooling passage of the blower housing is increased to 50° C. and, if the hydrogen flows at 1 g/s in the cooling passage, it is possible to radiate the heat of about 430 W.

The hydrogen supplied to the cooling passage 57 through the hydrogen supply line 58 can cool the motor through the heat exchange as described above. Moreover, with the heat insulating plate 60 dividing the inside of the blower housing into the impeller portion and the motor portion, it is possible to improve the heat radiation performance and further prevent condensation of the high-temperature mixed gas generated from the outlet of the fuel cell stack and flowing to the impeller 52.

As described above, the present apparatuses have the following advantages:

1) It is possible to improve the cooling efficiency of the motor and ensure the stability of the system by using a portion of hydrogen, used as fuel in a fuel cell, as a coolant for cooling the motor in the hydrogen recirculation blower;

2) With the increase in the capacity of the motor in the hydrogen recirculation blower, it is possible to increase the amount of hydrogen recirculation;

3) With the increase in the amount of hydrogen recirculation, it is possible to improve the durability of the fuel cell system; and

4) It is possible to increase the lifespan of the motor in the hydrogen recirculation blower.

The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. 

1. An apparatus for cooling a hydrogen recirculation blower for a fuel cell vehicle, wherein a portion of hydrogen, used as fuel in a fuel cell stack, is used as a coolant for cooling a motor of the hydrogen recirculation blower.
 2. The apparatus of claim 1, comprising: a blower housing including an inlet and an outlet for hydrogen recirculation provided in a front part thereof, and an impeller and a motor for driving the hydrogen recirculation blower provided therein; a cooling passage, through which hydrogen is supplied to the blower housing to provide heat exchange, provided to the blower housing; and a hydrogen supply line, through which hydrogen is supplied to the cooling passage to cool the motor, branched from a hydrogen supply pipe and connected to the blower housing.
 3. The apparatus of claim 2, wherein a heat insulating plate is provided on the inner wall of the blower housing so as to divide the blower housing into an impeller portion and a motor portion.
 4. The apparatus of claim 2, wherein the cooling passage is disposed on the outer surface of the blower housing in order to cool the motor heated by rotation of the impeller, and cooling fins are provided inside the cooling passage such that the hydrogen supplied to the cooling passage cools the cooling fins heated by the heat generated from the motor.
 5. The apparatus of claim 4, wherein a heat insulating plate is provided on the inner wall of the blower housing so as to divide the blower housing into an impeller portion and a motor portion. 